Refrigeration system



Jan. 24, 1967 w. T. OSBORNE 3,299,653

REFRIGERAIION SYSTEM Filed Oct. 20, 1965 INVENTOR. WILLIAM T. osoRNEATTORNEY.

United States Patent O 3,299,653 REFRIGERATION SYSTEM William T.Osborne, Syracuse, N.Y., assignor to Carrier Corporation, Syracuse,N.Y., a corporation of Dela- Ware Filed Oct. 20, 1965, Ser. No. 498,8154 Claims. (Cl. 62-115) This invention relates to a refrigeration systemand to a method of operating a refrigeration system and, moreparticularly, to recirculating residual liquid refrigerant through anevaporator by utilizing ilash gas in the system.

In various types of evaporators such as those having tube bundles overwhich refrigerant is sprayed or dripped, or through which refrigerant ispumped, for example, some means is usually required for recirculatingresidual liquid refri-gerant through the evaporator to lfully wet allheat exchange surfaces, thereby providing acceptable efficiency. Motordriven pumps are commonly -used for this purpose Kbut are expensive andoften troublesome.

It is a primary object of this invention to provide a new land improvedrefrigeration system and method of providing refrigeration. A relatedobject is to recirculate residual liquid -refrigerant collecting in thesystem. Another related object is provision for recirculating thisliquid refrigerant by utilizing flash gas.

These and other objects and advantages of the invention will be apparentfrom the following description and drawing which is la schematic flowdiagram of a refrigeration system embodying features of the invention.

The invention is equally applicable to various types of refrigerationsystems such as an absorption system or a compression system and isillustrated as embodied in a centrifugal compressor refrigerationsystem.

Referring to the drawing, refrigerant condensate passes from a condenser11 through a refrigerant condensate line 12 and iiow metering means suchas a float valve unit 13 vented to the condenser 11 through a vent line14. From the oat valve the liquid refrigerant passes through a ash gaschamber 15 and a refrigerant supply line 16 to a refrigerant inlet 17 ofan evaporator 18. The supply line 16 has a liquid seal loop 19 forsu-bstantially preventing passage of flash gas through the supply line16 into the evaporator 18 to maintain the chamber 15 above evaporatorpressure. The liquid refrigerant vaporizes in the evaporator 18 and iswithdrawn through a suction line 20 communicating with a compressor 21from which compressed refrigerant vapor passes through a highpressurerefrigerant line 22 to the condenser 11.

The illustrated evaporator 18 has a tube bundle 23 through which chilledwater is suitably circulated to a load having a cooling requirement. Therefrigerant entering the evaporator 18 through the refrigerant inlet 17passes into a drip pan 24 having a plurality of perforations in itsbottom wall through which the liquid refrigerant drips `over the tubeybundle 23 and is vaporized as the chilled water in the bundle iscooled. A portion of the liquid refrigerant passing over the tube bundle23 does not vaporize but collects in a sump 25 of residual liquidrefrigerant in the bottom of the evaporator 18 from which the residualrefrigerant is pumped back through a recirculating refrigerant line 26to the refrigerant inlet 17 and the :drip pan 24 for recirculation overthe tube bundle 23.

Pumping of the residual liquid refrigerant results from a high densityhead of this liquid refrigerant lifting a relatively lower densitycolumn of froth formed by mixing refrigerant gas with a portion of theresidual liquid refrigerant. More particularly, in order to pump theliquid refrigerant from the evaporator sump 25 to the evaporator inlet17, the illustrated embodiment of the recirculating refrigerant line 26is formed with -a loop 'having a depending portion 27 extendingdownwardly from Fice the sump 25y and communicating with .an ascendingportion 28 extending upwardly to the refrigerant inlet 17. Therefrigerant froth is formed in the ascending portion 28 of the line 26by passing refrigerant flash gas from the chamber 15 through a flash gasline 29 opening into the ascending portion 28 .at an elevationsuliiciently below the head of residual liquid refrigerant that thesubstantially lower density froth Imixture is lifted to the inlet 17.The Hash gas line 29 preferably extends through the recirculating line28 in sealed engagement therewith, and has a suitable mixing portion 30herein opening upwardly in the line 28 to mix the gas with the liquidrefrigerant to form the froth.

While a preferred embodiment of the invention has been described andillustrated, it should be understood that the invention is not limitedthereto but may be otherwise embodied -within the scope of the followingclaims.

I claim:

1. A method of operating a refrigeration system including a firstportion adapted to contain liquid refrigerant and a second portion .at ahigher elevation adapted to receive the refrigerant comprisingdispersing gas in a portion of said liquid refrigerant to form a mixturehaving a substantially lower density than the liquid refrigerant, andapplying the head pressure of said liquid refrigerant in said firstportion to said gas and liquid mixture to raise said portion of gas andliquid to said second portion.

2. A method of operating a refrigeration system including an evaporatorhaving an inlet for liquid refrigerant in an upper portion, a sum-p forresidual liquid refrigerant in a lower portion, yand conduit meanshaving a portion descending from said sump and a portion ascending tosaid inlet in which the steps consist in providing flash gas at apressure above the evaporator pressure during operation of the system,passing said flash gas into liquid refrigerant in the ascending portionof said conduit means below the level of said liquid refrigerant in said`conduit means to form a relatively low density mixture of refrigerantliquid and gas, and lifting said mixture to said inlet by the headpressure of liquid refrigerant in said descending portion.

3. In a refrigeration system, the combination of la first region adaptedto contain liquid refrigerant, a second region at an elevation higherthan the rst region ladapted to receive refrigerant from the firstregion, a line connecting the two regions having a descending portionand an .ascending portion adapted to contain liquid refrigerant, meansfor discharging gaseous refrigerant in the ascending portion of saidline below the level of liquid refrigerant therein to form a froth ofsubstantially lower density than the liquid refrigerant, said gaseousrefrigerant being discharged into the line at a position such that thehead of liquid refrigerant in said line raises the froth to the secondregion.

4. A refrigeration system comprising an evaporator and refrigerant inletmeans in an upper portion of the evaporator for the passage of liquidrefrigerant into the evaporator to vaporize and provide cooling, a sumpfor residual liquid refrigerant in a lower portion of the evaporator,means adapted to Withdraw the refrigerant vapor from said evaporator,means adapted to pass refrigerant to said evaporator including a ash gascharnber adapted to be at a pressure above the evaporator pressureyduring operation of the system, means adapted t-o -pass liquidrefrigerant to said chamber, means adapted to pass liquid refrigerantfrom said chamber to said inlet means, a line having a first portiondescending from said sump and a sec-ond portion ascending from the`descending portion to said inlet means for the passage of said residualliquid refrigerant to said refrigerant inlet means,

Iand means adapted to pass said residual liquid refrigerant through saidline to said inlet means including means communicating with said chamberand opening into said ascending portion of said line below the level ofsaid residual liquid refrigerant therein adapted to inject ash gas fromsaid chamber into the liquid refrigerant to form a relatively lowdensity mixture of refrigerant `liquid and gas, said flash gas beingdischarged into the line at a posi-tion such that the head lof residualliquid refrigerant lifts said mixture to said inlet means.

References Cited by the Examiner UNITED STATES PATENTS Jones 62--115lMcGrath et al. 62-512 X Anderson et al 62-117 Weller 62-525 X Chub'b etal. 62-498 0 LLOYD L. KING, Primary Examiner.

1. A METHOD OF OPERATING A REFRIGERATION SYSTEM INCLUDING A FIRSTPORTION ADAPTED TO CONTAIN LIQUID REFRIGERANT AND A SECOND PORTION AT AHIGHER ELEVATION ADAPTED TO RECEIVE THE REFRIGERANT COMPRISINGDISPERSING GAS IN A PORTION OF SAID LIQUID REFRIGERANT TO FORM A MIXTUREHAVING A SUBSTANTIALLY LOWER DENSITY THAN THE LIQUID REFRIGERANT, ANDAPPLYING THE HEAD PRESSURE OF SAID LIQUID REFRIGERANT IN SAID FIRSTPORTION TO SAID GAS AND LIQUID MIXTURE TO RAISE SAID PORTION OF GAS ANDLIQUID TO SAID SECOND PORTION.